I've been in communications with TT. They don't have another option to charge without having another dock. The charger they offer to be hooked up to the dock harness, which is just not a very well thought out system. They should be supplying a power port dock on a charger for site unit charging. Or they really should be reconsidering the amphora battery selection in your units. It should be stated that their system recommends a battery supply for proper operation.
My biggest con ern with operating without a battery is that when the TT draws down to a low battery level, it defaults my user settings, kicks our out of your buddy group and erases my tracks from the day.
TT is working on a solution they say.